Leak sensor for flowing electrolyte batteries

ABSTRACT

A leak detection system for a flowing electrolyte battery comprising a containment member associated with at least one of a stack of a flowing electrolyte battery and an electrolyte reservoir of a flowing electrolyte battery and a sensing member for sensing a fluid leak within the containment member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to flowing electrolyte batteries, and inparticular to a leak sensor for use in association with flowingelectrolyte batteries such as zinc/bromine batteries. It will beunderstood that the application is not limited to any zinc/brominebatteries or to any other particular flowing electrolyte battery.

2. Background Art

Flowing electrolyte batteries (Zn—Br batteries, V-Redox batteries, etc)are well known in the art for their quality power providingcharacteristics and their cycling ability. Generally, such batteriesrely on the circulation, by pumps, of electrolyte. As the circulation ofelectrolyte includes a multitude of components, fittings and conduits apotential always exists for failure of one of these components. Suchfailure will generally result in a leak of electrolyte.

In addition, since many such batteries require cooling systems whichlikewise comprise a multitude of conduits fittings and components, thecooling systems are likewise problematic. Failure in such componentsgenerally results in a leak of coolant. Further still, many suchbatteries, especially in industrial applications, are placed in asubstantially sealed container which remains exposed to harshenvironments. As such, damage to the sealed container often results inthe collection of precipitation within the container.

Any leak of electrolyte or coolant, as well as any entry of outsidemoisture can have catastrophic results. Specifically, not only will itcause the battery to operate in a less than optimal condition, thebattery may completely fail. For industrial applications, and especiallywhen used as an emergency power supply, such batteries must be ready forimmediate operation. If a battery fails, then it is incapable ofproviding power in an emergency. Thus, it is important to provide earlynotification of a leak in such a battery.

Moreover, in the event of a failure, it is important to contain anyleaks, thereby precluding contamination of the battery by the leakingfluid. By limiting the contamination caused by the fluid leak, thebattery can be more easily repaired and returned to operation.

Thus, it is an object of the invention to facilitate the containment ofa leak within a flowing electrolyte battery.

It is a further object of the invention to facilitate the detection of aleak of fluid within a flowing electrolyte battery.

SUMMARY OF THE INVENTION

The invention comprises a leak detection system for a flowingelectrolyte battery. The leak detection system comprises a containmentmember associated with at least one of a stack of a flowing electrolytebattery and an electrolyte reservoir of a flowing electrolyte battery,and, means for sensing a fluid leak within the containment member.

In a preferred embodiment, the sensing means comprises a switch, acontroller and a connector. The switch includes a first plate and asecond plate. Fluid within the containment member (i.e. a leak) servesto electrically couple the first plate to the second plate, to, in turn,close the switch. The controller is associated with the switch, and, thecontroller is capable of sensing the condition of the switch. Theconnector is electrically associating the switch and the controller.

In such an embodiment, the sensing means further comprises a resistorpositioned in parallel to the switch. In another such embodiment, the atleast one switch comprises a plurality of switches positioned inparallel.

In a preferred embodiment, the containment member comprises a stack leakcontainment member associated with at least one stack; and anelectrolyte reservoir leak containment member associated with at leastone reservoir. In one such embodiment, the sensing means is capable ofsensing a leak in each of the stack leak containment member and the atleast one electrolyte reservoir leak containment member.

In another aspect of the invention, the invention comprises a method fordetecting leaks in a flowing electrolyte battery. The method comprisesthe steps of (a) providing at least one containment member for at leastone of the stack and the reservoir; (b) providing at least one sensor;(c) positioning at least one sensor such that a leak collected in the atleast one containment member triggers the sensor; (d) providing acontroller; and (e) associating the controller with the at least onesensor, such that the controller is capable of electricallycommunicating with the sensor.

In one embodiment, the step of providing at least one containment membercomprises the steps of (a) providing a stack leak containment member;(b) positioning the stack leak containment member such that a leak fromthe stack is collected by the stack leak containment member; (c)providing a reservoir leak containment member; and (d) positioning thereservoir leak containment member such that a leak from the reservoir iscollected by the reservoir leak containment member.

In one embodiment, the step of providing a sensor comprises the steps of(a) providing a sensor for the stack leak containment member; and (b)providing a sensor for the reservoir leak containment member. In such apreferred embodiment, the step of positioning the at least one sensorcomprises the steps of (a) positioning a sensor in the stack leakcontainment member such that a leak collected in the stack leakcontainment member triggers the sensor; and (b) positioning a sensor inthe reservoir leak containment member such that a leak collected in thereservoir leak containment member triggers the sensor.

In another embodiment, the method further includes the step of sensing afluid leak. Preferably, the method likewise includes the step ofdetermining the type of fluid leak

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawings is a schematic representation of the presentinvention;

FIG. 2 of the drawings is a schematic representation of the sensor ofthe present invention;

FIG. 3 of the drawings is a schematic representation of multiple sensorsof the present invention; and

FIG. 4 of the drawings is a schematic representation of a secondembodiment of a sensor of the present invention

BEST MODE FOR PRACTICING THE INVENTION

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will be described in detail,one specific embodiment with the understanding that the presentdisclosure is to be considered as an exemplification of the principlesof the invention and is not intended to limit the invention to theembodiment illustrated.

Leak detection system 10 is shown in FIG. 1 as comprising stack leakcontainment member 12, reservoir leak containment member 14 and means 16for sensing a leak. Leak detection system 10 is for use in associationwith a flowing electrolyte battery, such as zinc/bromine battery 100.While various flowing electrolyte batteries are contemplated for use,the invention will be described with reference to a zinc/bromine batterysolely as an example. Generally, zinc/bromine battery 100 includes oneor more stacks, such as stack 102, electrolyte reservoir 104,circulating means 106 and means 108 for controlling the climate withinbattery 100. Stack 102 includes plurality of arranged anodes andcathodes so as to comprise a plurality of stacked cells. Electrolytereservoir 104 stores the electrolyte which is circulated by circulationmeans 106 through stack 102. In certain embodiments, a climate controlmeans 108 may be incorporated to either heat or cool the electrolyte soas to maintain the overall battery within operating parameters.

Electrolyte stack leak containment member 12 is shown in FIG. 1 ascomprising base 30 and sides 32 which define cavity 34. As will beunderstood, at least a portion of stack 102 is positioned within cavity34 such that, in the case of an electrolyte leak in stack 102, such aleak will fill cavity 34. In embodiments such as the embodiment shown inFIG. 1, wherein two vertically oriented stacks 102, 102′ form a tower,each stack has its own electrolyte leak containment member, 12, 12′. Insuch an embodiment, the upper electrolyte leak containment member 12includes overflow opening 36, which, in turn, directs any overflow ofelectrolyte into the lower electrolyte leak containment member 12′. Inthis manner, the spread of electrolyte can be minimized.

Reservoir leak containment member 14 is shown in FIG. 1 as comprisingbase 40 and sides 42 which define cavity 44. The electrolyte reservoirsare positioned within the reservoir leak containment member such thatany leak in the electrolyte reservoirs will be contained by thereservoir leak containment member. In addition, the reservoirs, and, inturn, the reservoir leak containment members are positioned below stack102 such that, in the event of a leak which overflows electrolyte leakstack containment member 12 (or 12′) will be directed into, andcontained by, reservoir leak containment member 14.

Sensing means 16 is shown in FIG. 1 as comprising sensor 50, controller52 and connector 54. Sensor 50, as shown in FIG. 2, includes baseresistor 60 and switch 62. Switch 62 is in parallel with resistor 60 andincludes surface 70 and surface 72. As will be explained in detailbelow, in the event of a leak, the leaking fluid contacts surface 70 andsurface 72, to, in turn, close the circuit, essentially forming aswitch. While other shapes are contemplated, the surfaces 70, 72comprise mesh surfaces. Such mesh surfaces provide a relatively largesurface area for contact of the fluid with the mesh surfaces. Whilevarious systems are contemplated, resistor.60 comprises a resistorhaving a value of 3000 .OMEGA., and the voltage applied to switch 62 andresistor 60 is 24V. Of course, various other circuits are contemplated,wherein the applied voltage may be either lower or higher, and, variousresistors are contemplated for use. In other embodiments, the resistormay be omitted wherein the controller views the circuit as an opencircuit until such time as the switch is closed.

Connector 54 connects controller 52 to sensor 50 such that controller 52is capable of sensing the closing of a switch 62 of sensor 50. As willbe explained below, if fluid from a leak provides a closed circuitacross surfaces 70, 72, then the resistance of the parallel combinationof the switch and the resistor effectively decreases, and the current inthe system increases (i.e. voltage remains constant, and thereforevoltage is equal to resistance times current). Controller 52 comprises adigital microcontroller capable of reading the current change across theresistor and the switch. Of course, various analog or digital systemsare contemplated for use.

In operation, a flowing electrolyte battery is first equipped with leakdetection system 10. Specifically, stack leak containment member 12 isprovided for each stack and each stack is positioned so that a portionis within cavity 34. Additionally, electrolyte reservoirs 104 arepositioned within electrolyte reservoir leak containment member 14.

Once the containment members are positioned, sensors 50 are positionedwithin the cavity of each stack leak containment member. Subsequently,sensors are likewise positioned within the reservoir leak containmentmember, and likewise in the bottom of the unit (in case of overflow fromany of the containment members). Once positioned, each sensor isattached to one or more controllers, such as controller 52, viaconnectors 54. The sensors are positioned such that a leak that collectsin any of the respective containment members (or at the bottom of theunit) will close a circuit about the surfaces 70, 72 of the respectiveswitch 62, which can be sensed by controller 52. Generally, to achieveearly recognition of leaks, the sensors are generally positionedproximate the lowest point of the respective containment member.

From time to time, the flowing electrolyte battery can experience anelectrolyte leak in, for example stack 102. In such an instance, theelectrolyte leak will collect in the respective stack leak containmentmember 12. As the level of electrolyte in the stack leak containmentmember increases, eventually, electrolyte will contact both surface 70and surface 72 of switch 62, thereby effectively closing the circuit. Asa result, the current in the circuit will tend to increase, and theincrease is sensed by controller 50. Controller 50 can then provide sometype of final output (i.e. audible, visual, radio, infra red, connectionto a main control unit, etc.) so that a user can be informed of theleak.

Similarly, a leak in the reservoir will tend to cause electrolyte toenter into the reservoir leak containment member. As the level ofelectrolyte increases in the reservoir leak containment member,electrolyte will contact surfaces 70 and 72 of the sensor positionedwithin the reservoir leak containment member and the switch will beeffectively closed by the electrolyte. In turn, the circuit will exhibitan increased current which will be sensed by the controller.

It will be understood that in certain embodiments which utilize a liquidcoolant, a coolant leak can occur. Such a coolant leak will generallycollect in the base of the unit or in the reservoir leak containmentmember. As with the electrolyte leak, as the coolant level rises, thecoolant will contact the surfaces 70 and 72 of one of the sensors,thereby effectively closing the switch.

Again, the controller will recognize the closing of the switch. Indeed,any fluid collection (i.e. electrolyte leak, coolant leak, condensation,outside precipitation) within any of the containment members orproximate the base of the flowing electrolyte battery will trigger asensor switch to close. Since each such fluid generally comprises adifferent resistivity (i.e. the electrolyte generally exhibits lesselectrical resistance than coolant or water (contaminated)), currentchanges sensed by the controller will be different based on the fluidthat is causing the closing of the respective switch. In turn, thecontroller can be programmed to distinguish between the different leaks.In this case, if the controller determines that the cause of the leak iscondensation, there is no need to service the battery or to take thebattery out of operation.

In another embodiment, as shown in FIG. 3, the sensor may comprise aplurality of switches in parallel with a single resistor. In such anembodiment, each switch may be positioned in a different area, such asthe stack leak containment member, the electrolyte reservoir leakcontainment member and the overflow area of the housing. As such, a leakin any one of these areas will cause fluid in the respective area toclose the switch, and in turn, lower the overall resistance of thecircuit. The lower resistance (and increased current) is then sensed bythe controller which is attached to the sensor. In such an embodiment,the controller can signal a leak, however, the precise location of theleak is not known.

In another embodiment, as shown in FIG. 4, sensor 50 may include anadditional switch, namely, switch 63 which is positioned in parallel toswitch 62 and resistor 60. When installed, switch 63 is positioned lowerthan switch 62 such that a leak will first close switch 63 before theleak closes switch 62. As will be understood, a small leak will tend toclose switch 62, whereas a large leak will tend to close switch 63 andswitch 62. As a result, the controller will receive a first currentreading increase as the leak closes switch 63 and a second currentreading increase as the leak closes switch 62. Accordingly, thecontroller can be used to access the severity of the leak.

The foregoing description merely explains and illustrates the inventionand the invention is not limited thereto except insofar as the appendedclaims are so limited, as those skilled in the art who have thedisclosure before them will be able to make modifications withoutdeparting from the scope of the invention.

1. A leak detection system for a flowing electrolyte battery having ahousing and a plurality of stacked cells within the housing, andelectrolytic fluid circulating through the interior of the stackedcells, the system comprising: a stack leak containment member within thehousing, the stack leak containment member disposed underneath of andsurrounding at least a portion of the plurality of stacked cells, thestack leak containment member collecting electrolytic fluid leaking fromthe plurality of stacked cells; and a sensor disposed in a space betweenthe interior of the stack leak containment member and exterior to thestacked cells, the sensor detecting the presence of uncirculatedelectrolytic fluid in the space when the uncirculated electrolytic fluidcontacts the sensor; the sensor having: at least one switch comprising afirst plate and a second plate; wherein uncirculated fluid within thestack leak containment member forms an electric current path between thefirst and second plates; a controller associated with the switch, thecontroller capable of sensing presence or absence of the current path;and a resistor connected in parallel to the switch.
 2. The system ofclaim 1 wherein the at least one switch comprises a plurality ofswitches connected in parallel.
 3. The system of claim 1, the pluralityof stacked cells comprising at least two vertically stacked assembliesof stacked cells, with each assembly including a corresponding stackleak containment member; wherein at least one upper stack leakcontainment member associated with an tipper assembly of the at leasttwo stacked assemblies includes an overflow opening which directs anoverflow of the uncirculated electrolytic fluid into a lower stack leakcontainment member associated with a lower of the at least two stackedassemblies.
 4. The system of claim 3 wherein the upper and lower stackleak containment members include corresponding sensors for detectingpresence of an uncirculated electrolytic fluid.
 5. The leak detectionsystem of claim 1 wherein the controller includes a means for signalingthe condition of the sensor to a user.
 6. The leak detection system ofclaim 1, wherein the sensor comprises resistivity measurement circuitry.7. The leak detection system of claim 6, further comprising: leakdetection logic, the leak detection logic in electrical communicationwith the resistivity measurement circuitry; wherein, the leak detectionlogic determines the presence of uncirculated electrolytic fluid based,at least in part, on the output of the resistivity measurementcircuitry.
 8. The system of claim 1, comprising: an electrolytereservoir for supplying electrolytic fluid to the plurality of stackedcells, said electrolyte reservoir having a reservoir leak containmentmember disposed underneath and exterior to the electrolyte reservoir,and a reservoir sensor disposed in a space between the interior of thereservoir leak containment member and exterior to the electrolytereservoir, the reservoir sensor detecting the presence of fluid in thespace between the interior of the reservoir leak containment member andthe exterior of the electrolyte reservoir.
 9. The system of claim 8,wherein the stack leak containment member is located above the reservoirleak containment member and includes an overflow opening which directsan overflow of the electrolytic fluid into the reservoir leakcontainment member disposed underneath the stack leak containmentmember.
 10. A leak detection system for a flowing electrolyte batteryhaving a reservoir containing electrolytic fluid, comprising: areservoir leak containment member disposed underneath and exterior tothe reservoir, the reservoir leak containment member collectingelectrolytic fluid leaking from the reservoir; and a sensor disposed ina space between the interior of the reservoir leak containment memberand exterior to the reservoir, the sensor detecting the presence ofuncirculated electrolytic fluid in the space between the interior of thereservoir leak containment member and the exterior of the reservoir. 11.A leak detection system for a flowing electrolyte battery having ahousing and a plurality of stacked cells within the housing, andelectrolyte fluid circulating through the interior of the stacked cells,the system comprising: a stack leak containment member within thehousing, the stack leak containment member disposed underneath of andsurrounding at least a portion of the plurality of stacked cells, thestack leak containment member collecting electrolyte fluid leaking fromthe plurality of stacked cells; a sensor disposed in a space between theinterior of the stack leak containment member and exterior to thestacked cells, the sensor detecting the presence of leak electrolytefluid in the space when the leak electrolyte fluid contacts the sensor;an electrolyte reservoir for supplying electrolyte fluid to theplurality of stacked cells, said electrolyte reservoir having areservoir leak containment member disposed underneath and exterior tothe electrolyte reservoir, and a reservoir sensor disposed ma spacebetween the interior of the reservoir leak containment member andexterior to the electrolyte reservoir, the reservoir sensor detectingthe presence of fluid in the space between the interior of the reservoirleak containment member and the exterior of the electrolyte reservoir;wherein the stack leak containment member is located above the reservoirleak containment member and includes an overflow opening which directsan overflow of the electrolyte fluid into the reservoir leak containmentmember disposed underneath the stack leak containment member.
 12. A leakdetection system for a flowing electrolyte battery having a housing anda plurality of stacked cells within the housing, and electrolyte fluidcirculating through the interior of the stacked cells, the systemcomprising: a stack leak containment member within the housing, thestack leak containment member disposed underneath of and surrounding atleast a portion of the plurality of stacked cells, the stack leakcontainment member collecting electrolyte fluid leaking from theplurality of stacked cells; a sensor disposed in a space between theinterior of the stack leak containment member and exterior to thestacked cells, the sensor detecting the presence of leak electrolytefluid in the space when the leak electrolyte fluid contacts the sensor;leak detection logic, the leak detection logic in electricalcommunication with the sensor; wherein, the leak detection logic iscapable of discriminating between the presence at the sensor ofcondensation and leak electrolyte fluid based, at least in part, onmeasurement of resistivity of fluid at the sensor.